Rohm makes smartphone fuel cell

LONDON – Semiconductor and passives company Rohm Co. Ltd. (Kyoto, Japan) has developed a hydrogen fuel cell that can be used to recharge mobile phones and other portable electronic equipment.

Fuel cells can be made smaller, lighter and more efficient than conventional storage and rechargeable cells, and have the advantage of being more ecologically friendly, Rohm stated.

This series of hydrogen fuel cells uses a solid that creates hydrogen by adding water using the water droplet method. The result is power with no harmful by-products such as carbon dioxide or volatile organic compounds. As a result the fuel cells can be disposed of as general waste.

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Rohm, working with Aquafairy Corp. (Kyoto, Japan) and Kyoto University, has succeeded in solidifying calcium hydride in a sheet configuration. This allows the generation of about 4.5 liters of hydrogen from a sheet that measures 38-mm by 38-mm by 2-mm thick, which is less than 3 cubic centimeters in volume. This source of hydrogen weighs about 3 grams and provides an energy output of 5-watthours and allows the cell to fully charge a smartphone in less than two hours, according to Rohm.

The hydrogen fuel cells are compact and can operate at ambient temperatures, making them suitable for use in smartphone chargers, tablet PCs, as power sources outdoors and in remote areas, and in emergency backup power supplies. Rohm has two formats for smartphone chargers, an enclosure version measuring 140-mm by 65-mm by 20-mm and a card case format measuring 86-mm by 52-mm by 19-mm. Operating temperature range for both is -5 degrees to +40 degrees C.

Calcium hydride sheet material. Source: Rohm.

They also have an advantage over lithium-ion batteries and direct
methanol fuel cells can only store energy for a limited time. The
hydrogen fuel cells use laminated aluminum to enable storage without
losing energy of more than 20 years, Rohm claimed.

Construction of hydrogen fuel cell. Source: Rohm.

In addition to producing hydrogen fuel cells for smartphone chargers, Rohm and Aquafairy, in collaboration with Kinkei System Corp., are also developing fuel cells for powering seismometers in remote areas that prevent the use of traditional power supplies. Compared with conventional lead batteries with the same energy capacity, the hydrogen fuel cells reduce weight by 25 percent, making it possible to provide 400-Whr from a device that weighs 3kg, Rohm said.